Evaporator.



` o. snERLuND- EVAPORATOR.

` APPLICATION FILED ocT. al, 191|.

3 SHEETS- SHEET 3.

Patented Aug. 17, 1915.

- sTATEs PATENT oEEIoE.

oLoE sDEaLUND, or LoNDoN, ENGLAND, AssIGNon To TECHNO-CHEMICALLABORATORIES, LIMITED, or LoNDoN, ENGLAND.

EVAIPORATOR.

Application filed October 31, 1911.

subject of the King of Sweden, ,and residing' at Fairlawn, ClarenceRoad, Clapham Park, London, S. W., England, have invented a certain newand useful Improved Evaporator, of which the following is aspecification.

This invention relates to improvements 1n connection with theevaporation, distillation or concentration of liquids, and' similaroperations. l

I desire it to be understood that the term evaporator hereinafteremployed is intended y to include apparatus suitable for any one or moreof the above operations.

By the present invention, evaporation may beeected in an apparatuswithout the employment of more than a s mall amount, if any, of externalheat supplied as such to the apparatus. A

According tol the present invention, the vapor given of by the liquidwhich is being evaporated in an evaporator is withdrawn, compressed, andutilized as a heats ing medium for effecting or assisting in urtherevaporation by virtue of the inf crease of temperature which it hasundergone owing to compression, the vapor being preferably for thispurpose supphed after compression to a heating device to the heatingaction of whichthe liquid to be evaporated is exposed in a nely dividedcondition e. g. as a very thin lilm. For

the eflicient working of such/an apparatus and therefore to allow of themost advantageous commercial'utilization of the same the exposure of theliquid in a thin lm is most important since if the heating device iscaused to act upon a large body of the liquid to be evaporated a higherdifference of temperaturebetween the vapor in the heating element andthe' liquid it is heating' (and thereforea higher compression) is`required than ifthe vapor has only to heat a thin film of the liquid.

To this Yend apparatus for carrying out the present method in itspreferred form comprises an outer vessel provided with a gas eductconnected to a compressor, the outlet of which is connected to iuidheated heating means, over which the liquid to be A distilled orconcentrated is caused to iow in a thin film as by causing it to fallin. a rain upon the upper part of the heating means. By causing theliquid which is to Specification of Letters Patent.

compression is now above that v Patented Aug. 17, l1915. serial No.657,738.

be evaporated to flow over the heating element 1n a thin lm the freesurface of the liquid is in this way largely increased and Y theevaporative efficiency of the device en'- hanced thereby.

The accompanying drawings show in.Fig-- ure 1 a vacuum evaporator 1nsectional ele-l vation, and in Figs. 2 and 3.a modified form ofevaporator in part sectional, front and side elevation, respectively.

Referring to Fig. 1, a cylindrical chamber a has a gasor vapor outletpipe f, connected to a suction compressor g supplying a coil a through apipe The coil 'i is extended into a chamber t formed outside the mainchamber, and passes thence into a reservoir u having an automaticblow-oil' fu, and an outlet for condensed vapors at w. The lower part ofthe main chamber is provided with a pipe Z connected to a pump m, whichsupplies aliquid distributing device 0, (which is adapted to distributethe liquid as a rain upon the upper part of the coil i) by means of .apipe n. A funnel shaped element fr, with the draw-olf pipe y apparatuscontinuously. A feed tank 1 supplies a distributing device 2 through acock 3,

the element 2 being adapted to distribute liql uid over the lowerportion of the coil pipe z'.

provided. Th suitable points in the apparatus.

and cock z, is provided to allow of using the AThe Operation of thedevice is as fol-* lows Assuming the apparatus to have been suitablyheated up las by introducing ,steam by the cock, vg, drawing it o'ff bythe element g, po mpressing it, and passing `itinto, the co1 z, flowfrom the distributing device 2 over the lower part of the tube andbecomes warmed. It flows into the lower part 'of the chamber a, throughthe'pipe l, and is pumped by the pump m through the pipe 'n to thedistributer e which causes it to flow in a relatively thin-film wherebyits free surface is also largely increased over the hot coil z',Evaporation occurs, andthe vapor evolved is sucked away by the'element gcompressed to raise its temperature suiciently, Y and then passesthrough the pipe L'into the coil i. VAs its` temperaturejby virtue ofthe of the `liquid contacting with the tubes, it causes evaporatheliquid to be heated is caused to 1oz-sV say by some 5 degreescentigrade, g

tion of the liquid. The vapor inl the coil i condenses, and thecondensed vapor lgives -f out its heat in flowing -down `thelcoil,`.tovthe liquid distributed overv it, both inthe cham# ber a and in thechamber't, leading'thejcoil through the cock-'8, and entering-thechambers u, from which the air accompaying@they` condensed liquid canescape atl fv', landthe'.

lliquid passes away at w. The liquid, after ilowing over the c oil z',collects in the funnel and passes out through the plpe y and cock e, ifthe apparatus is employed to effect f the desired concentration in onepassage of the liquid through the apparatus or the cock .e is partly orquite closed, when the liquid overilows from the funnel fr, and is thenreturned to the distributer as often as desired before withdrawal. Byintroducing the steam for initially heating up the apparatus into theevaporation chamber a. instead of may be evolved from the boiling liquidand accumulate on the surface of the' liquid.

Such accumulation interrupts the active circulation of the vapors inthe'outer chamber and it is-therefore desirable to promote thecirculation in this way. Active circulation of the vapor in theapparatus assists theevaporation materially. rIhe cock 4 gives means ofsampling to ascertain when the desired concentration is attained such acase. The gage 6 allows of observing the amount of liquid in theevaporator. The low of condensed liquid from the coil i is, by the cock8, controlled to keep upthe desired pressure in the coil. It will beunderstood that all the exposed parts of theapparatus are lagged, orlosses by radiation are in any other suitable manner reduced to aminimum. Inthis way.- it

'becomes possible to concentrate lorjdistil liq-` u1d introduced intothe apparatus, by utiliz-y ing the increase in temperature of the vaporevolved from the liquid, when the same is compressed.

In Figs. 2 and 3 which has been ,employed for the distillation'of'w'aten Theevaporating chamber is in this case flat, and formedof-plates c and d, bolted'toa rim b. i Thefplates have win-r dows e forinspecting the liquid distributingv device o, and for'ascertaining theamount. of

i liquid in the chamber. 'Y A pipe f issues from the top of the chamber,and is connected to a rotary compressor g, e. g., a Roots blower, whichsupplies through the pipe h the serpentine composed of pipes iconnected'to is show-nan experimental vapparatus constructed on theabove lines,

ybends j.l At 7c is an outlet for condensed water, and. at l is apipeadapted to conduct liquid from the chamberto apump m,which supplies itto vthe distributing pipe o, having 'perforations p through a pipe n. Atg is the pipeby which steam'may be introduced, vfor initially` heatinup. the apparatus, and v at 1' is apipe by which the liquid to be evaporated .may be introduced.` The whole apparatus is mounted in aframework Vs and is providedwith'.thermometers 7, as abov'e. 'In ordertoobtain the 'best eiiciency from such an apparatus, it will be understoodthat i vthe heat contained in the outiiowing condensed liquid shouldberegenerated, .as completely as possible, and this may be eiected by anysuitable coil or other heat`exchangv ing device. Atthe Sametime, thepre-heating effected in this way can be utilized to free the liquidentering the apparatus form air,I so that only vapor free from air orether non-condensible gases is evolved from the liquid when Iit reachesthe evapora] As,

however, the heat obtained by this Preheat-i ing may not be suiiicientfor this purpose, it may be necessary to provide aspecial device, inwhich the additional heat necessary for this purpose may be provided byinjection of steam into the liquid. It will be understood that whereanapparatus ofl this "of solutions' of solids, care'should be taken 'fktfavoid any concentration todryn'ess in the apparatus, with consequentchoking up ofthe parts. w

The operation ofthe deviceushown in Figs. 2 and, 3 is'the same asthatabove described with reference to Fig. 1. When distilling fwater.experimentally in the latter apparatus, usin'g a temperature differencebetween the outlet and 'inlet of the compressorof about 4degreescentigrade, 'that is, temperatures ofabout 100 degrees and 105 degreescentigrade, respectivel obtainable by a compression equal to a outonetenth of an atmosphere, -which is sufficient vintheapparatusdescribed, I have reached figures whichi-a pear to' give anevaporative 'capacityrsevera .tifxnes 'greater than that .ob-

ultiple e'ect evapo talnable in rpresentrator practice'.` f

The c' mpressed vapor or -'steam passing into 'the heatingv tubes willcontain. Amore heat than isrequiredto evaporate an equivalent quantityof liquid from the fresh liquid to be evaporated, since compression ofthe vapor has raised iits temperature not' only to' a higher'temperature corresponding to the higher pressure, but it has alsosuperheat'ed the same to some.- extent, as canbe readily calculated. Inthis way it is theor'etically possibleto, generate the same amount. ofsteam without adding more heat to the system, except that mechanicalcompression, w 'ch also can be character is employed,`for theconcentration plrod'uced by the' n.

made wholly or partially to compensate losses due to radiation and thetemperature of the outlowing condensed liquid, which leaves at a highertemperature than the iniowing liquid. The latter may, however, bereduced to a minimum by heating the incoming liquid from the outgoingcondensed liquid as referred to.

The method and apparatus according to the present invention is ofparticular advantage where fuel is scarce, but where means forgenerating mechanical power, such as falls of water, are readilyavailable.

In order to make this evaporation system as economical as possible, itis of importance to employ only enough difference of pressure betweenthe two sides of the heating surface as is necessary to insure adierence of temperature giving satisfactory heat transmission. The heattransmission will be increased not only by raising 'the temperature butby providing good and rapid circulation, which can be done as aboveindicated, by pumping the liquid from the lower part of the evaporatorto the upper part, where it is distributed over the upper heating tubes,from which it streams down over the lower ones and back to the pumpagain, being continuously `diluted with fresh incoming liquid,concentrated liquid being drawn off either intermittently orcontinuously, as desired.

Having now described my invention what I claim as new and desire tosecure by Letters Patent is 1. A method of evaporating liquids in whichthe liquid is heated to boiling and the vapor therefrom compressed, thecompressed vapor being caused to impart heat to the liquid to attain atemperature at most 5 C. above the boiling temperature of the liquidundergoing evaporation, which is kept continuously exposed to theheating action of the vapor as a downwardly owing thin' film until thedesired degree of concentration is obtained; as set forth.

2. A method of evaporating liquids, consisting in 4spreading the'liquidas a downwardly flowing thin film over a heating element, collecting thevapor evolved from said film, compressing said vapor to raise itstemperature at most 59 C. above the boiling temperature of the liquid,and introducing said compressed vapor into the heating element, as setforth. Y

3. A method of evaporating a liquid consisting in heating the liquid toboiling, coloLoF SDERLUND.`

Witnesses:

BERTRAM HARRY MATTHEWS, E. C. WALKER.

